Cam followers are used extensively in indexing mechanisms in indexing devices, cam mechanisms in machine tools, paper feeding mechanisms in printing machines, etc. Specifically, cam followers serve as guides in operation mechanism in a variety of general equipment such as in conveyer systems of lifting and other material handling equipment, in transportation guides of pressing apparatuses, in sliding mechanisms of automatic doors, in fork extraction mechanism in fork lifts, and in many more. In a printing machine, cam followers are used in a shaft motion mechanism for paper retaining claws in a paper feeding system, in ink distribution rollers, in cam mechanisms, and so on.
Generally, a cam follower is a component which includes a cam follower stud (hereinafter simply called “stud”), and a thick-walled outer ring which is rotatably fitted to an end of the stud via rolling elements. The stud supports the outer ring in a cantilever manner, the outer ring makes a rolling movement on a track, and so cam followers are also called track rollers (Patent Literature 1, 2 and 3).
As shown in FIG. 27, a conventional cam follower is composed of a stud 1, and a bearing assembly 2 which is assembled rotatably to an end of the stud 1. The stud 1 has, on its one end, a bearing support portion 3, to which the bearing assembly 2 is rotatably fitted; and on the other end, a mounting shaft portion 4. The bearing support portion 3 has an end facing away from the mounting shaft portion 4, i.e. an outer end portion, where there is a flange portion 5 which serves as an outer end limiter for the bearing assembly 2.
The bearing support portion 3 has another end portion closer to the mounting shaft portion 4, i.e. an inner end portion, where there is a side plate fitting portion 7 which has a diameter reduced by a stepped portion 6. On an axially more inner side as viewed from the side plate fitting portion 7 is the above-described mounting shaft portion 4 which has a slightly more reduced diameter. The mounting shaft portion 4 has its tip portion formed as a thread portion 8. The stud 1 has an oil hole 10 formed therein.
The bearing assembly 2, which rotates on a track surface provided by an outer diameter surface of the bearing support portion 3, includes rollers 9 held by a retainer 11, and an outer ring 12 fitted thereto via the rollers 9. The side plate fitting portion 7 is press-fitted with an annular, inner side plate 13 which serves as an inner end limiter for the bearing assembly 2. The inner side plate 13 has the same outer diameter as the flange portion 5.
The outer ring 12 has two end surfaces, one provided with an annular outer end recess 14 and the other provided with an inner end recess 15, both provided coaxially. The outer end recess 14 is fitted with the flange portion 5 with slight radial and axial gaps. The inner end recess 15 is fitted with the inner side plate 13 with slight radial and axial gaps. The flange portion 5 and the inner side plate 13 limit axial movement of the bearing assembly 2.
The cam follower is fixed in a cantilever manner to the apparatus served thereby. The mounting shaft portion 4 of the stud 1 is inserted into a housing of the apparatus so that the thread portion 8 will protrude from inside to outside of the housing, and then a nut is threaded and tightened around the thread portion 8. The rolling element may be an encased roller type which uses a retainer, or a full-type roller bearing which does not use a retainer.
Generally, the stud 1 is made by means of cutting process. A metal rod is cut to form each of the above-described portions. Usually, before the cutting process, one end surface, i.e. an end surface to become an outer end surface of the flange portion, is formed with a hexagonal hole while the other end surface, i.e. an end surface to become an outer end surface of the mounting shaft portion, is formed with a center hole, by forging (Patent Literature 2).
Also, it is public knowledge that the track portion is provided with a lubrication structure provided by an axial oil hole 10 extending from the center of an outer end surface in the mounting shaft portion 4 of the stud 1 to the center of the track surface in the bearing support portion 3. The axial oil hole has an open end provided with a grease nipple (see Patent Literature 1 or 2).
Also, the recesses 14, 15 are provided with seal grooves 16, 17 respectively. These seal grooves 16, 17 are fitted with an outer end lip seal 18 and an inner end lip seal 19 respectively. Each of the lip seals 18, 19 has a lip 21 (see FIG. 28A), which is fitted so as to bend outward (in a direction from inside the bearing assembly 2 toward axially outside and away therefrom). The bent lips 21 are in contact with the outer diameter surfaces of the flange portion 5 and the inner side plate 13, thereby providing sealing.
As illustrated in the drawing, a chamfer 22 is provided along each corner region in the flange portion 5 and in the inner side plate 13 where their outer diameter surfaces meet their respective axial end surfaces, in order to prevent chipping and other problems which can develop at the corner regions.